If you arrive by plane at Malpensa:
Take the Malpensa Express (shuttle train to Milan). Get off at Saronno (second stop) and, from there, take a train to Milan that stops in Novate Milanese. If not, do not get off at Saronno but continue to the Bovisa station. There, take a train towards Saronno that returns to Novate Milanese (2 stops).